Would AI be appropriate for converting unstructured text into an XML?
A rule-based approach will guarantee a correct result, and it works perfectly fine. On the other hand, an AI based approach will introduce errors as AI cannot produce result with 100% accuracy, and also decreasing speed. As the document you are processing is a legal document, it would be better to use a parser as AI is only adding unnecessary wasted time and non-accurate results.

Hope I can help you.